Cleanable core barrel



J. E. TALBOT CLEANABLE CORE BARREL Filed June 29, 1953 JQCK 5, 7751507 INVENTOR July 19, 1955 United States Patent CLEANABLE CORE BARREL Jack E. Talbot, Bakersfield, Calif.

Application June 29, 1953, Serial No. 364,530

2 Claims. (Cl. 255-72) This invention relates to improvements in core barrels, and may be regarded as an improvement on the core barrel disclosed in United States Letters Patent No. 2,073,- 876, issued March 16, 1937 to Guy C. Oliver.

Explanatory of the present invention, in the course of drilling wells with a rotary well drilling apparatus there are times when it is desired to cut and withdraw a core of the formation penetrated for purposes of examination. In the usual procedure the well bore has been drilled with one or more forms of conventional drilling bit and when it is desired to recover a core, the core barrel is substituted for the drilling bit on the end of the drill string. During the period in which the drilling string has been withdrawn from the well and a substitution is being effected, it frequently occurs that cuttings settle to the bottom of the hole so that when the core'barrel is lowered into the well for the purpose of cutting a core the core barrel must first penetrate through these settled cuttings. The settled cuttings, of course, enter the barrel of the core barrel and may completely till it so that these cuttings hinder or prevent the entry of the core into the barrel. Consequently, in the course of cutting a core only a short portion of core which is only a small fraction of the capacity of the barrel can be cut and recovered.

The filling of the core barrel with unwanted material may also arise from other circumstances. Such as for example, during the lowering of the core barrel into the Well it may encounter materials on the well walls and the barrel may be filled or partially filled thereby. These materials, if they are allowed to remain in the barrel will hinder or prevent the cutting and recovery of a substantial length of core.

A primary object of the invention is to provide an im proved core barrel wherein provision is made for causing a portion of the circulation fluid for drilling mud to be discharged downwardly through the barrel when the core barrel is at or near the bottom of the well and is in the position to commence cutting the core. In this manner any foreign material such as settled cuttings that may be disposed within the barrel can be flushed out, enabling a core to be cut and recovered which is commensurate with the entire capacity of the barrel. After the inner barrel has been flushed out the entrance for circulation fluid is closed so that during the cutting of the core no circulation fluid is discharged downwardly through the barrel which would have a tendency to Wash away or disturb the cut core.

The invention while applicable to diiferent styles of core barrels, is particularly applicable to the type of core barrel disclosed in the above-mentioned patent to Guy C. Oliver wherein there is a core bit mounted on the bottom of an outer shell which in turn is attachable to a drill string. Supported on the core bit and within the shell there is an outer barrel and in inner barrel is rotatably supported therewithin. An outlet is provided at the top of the inner barrel to facilitate the entry of the core and as the inner barrel is in efliect protected by the outer barrel "ice danger of washing away the cut core is effectively prevented.

With the foregoing and other objects in view, which will be made manifest in the following detailed description and specifically pointed out in the appended claims, reference is had to the accompanying drawing for an illustrative embodiment of the invention, wherein:

Figure 1 is a vertical section through the improved core barrel illustrating the parts in that position during which the barrel can be flushed out by a portion of the circulation fluid;

Fig. 2 is a vertical section through the upper portion of Fig. 1, and illustrating the entrance for circulation fluid as having been closed so that the core may be out without being disturbed thereby; and

Fig. 3 is a horizontal section taken substantially upon the line 33 upon Fig. 2 in the direction indicated.

Referring to the accompanying drawing wherein similar reference characters designate similar parts throughout, the improved core barrel comprises a core bit 10 connected by means of an adapter 11 to an outer shell 12. This shell is threaded at its upper end as indicated at 13 enabling it to be connected such as by a sub 14 to the bottom of a string of rotary drill pipe indicated at 15. Within the shell 12 there is an outer barrel 16 threadedly mounted as indicated at 17 on the core bit. This outer barrel is closed at its top by means of a cap 18 and is disposed in spaced relation to the shell, the space being indicated at 19. The cap is preferably provided with radial ribs 26 which tend to stabilize the outer barrel 16 within the shell 12. These ribs, however, do not interfere with circulation fluid down through the space 19 and out through ports 21 in the core bit 19.

Within the outer barrel 16 there is an inner barrel 22 which has a core catcher, generally indicated at 23, at the bottom thereof. This inner barrel is rotatably disposed within the outer barrel 16 and is disposed in spaced relation thereto. The top of the inner barrel is closed by a cap 24 in which there are outlet ports 25 which provide communication between the top of the inner barrel and the space 26 between the inner and outer barrels. An anti-friction thrust bearing 2'7 is disposed between the cap 24 and a hollow threaded stern 27a which threadedly extends through the cap 18 on the outer barrel and is locked in adjusted position by means of a jamb nut 28. Stuifing boxes 29 and 30 protect the anti-friction bearing 27 against ingress of circulation fluid and abrasive materials.

The stem 27a has a vertical axial passage 31 therethrough at the top of which there is a valve seat 32. At the top of the stem there is applied a ball catcher 33 carrying a cage 34. This ball catcher is designed to catch a ball valve 35 which can be dropped through the drill string 15 when it is desired to close the passage 31. The valve 35 is of such a size that it cannot pass between the edges of the ball catcher 33 and the top of the outer shell 12, but it can enter between the arms of the cage 34.

In assembling the core barrel, the inner barrel 22 is positioned within the outer barrel 16 and the outer barrel is screwed into the core bit 16. it is important that a close adjustment be secured so that although the inner barrel 22 is rotatable within the outer barrel 16 that there be no excessive clearances or sloppy movements. This adjustment can be accomplished by loosening the jamb nut 28 and adjusting the stem 27a relatively to the cap 18. The upward or downward screwing of the stem relative to the cap enables a fine or close adjustment of the inner barrel 22 to be secured after the inner and outer barrels have been mutually assembled. This adjustment is maintained by tightening the jamb nut 28. The mutually assembled inner and outer barrels and the core bit are then attached to the adapter 11 and the within the inner barrel.

J outer shell is attached to the drill string and is lowered thereby into the well.

As above explained, as the core barrel approaches the bottom of the Well hole it may encounter a large mass of cuttings which have settled to the bottom of the well. These cuttings may enter and largely fill the inner barrel 22 and if allowed to remain therein they would interfere with the entry of the desired core. Consequently, in preparing to cut a core with the improved core barrel, the core barrel is held a short distance off-bottom and circulation fluid is forced down through the drill string 15. A substantial portion of this circulation fluid is caused to pass down through the passage 31 in the hollow stern 27a and to be discharged down through the inner barrel 22, flushing out all of the cuttings in the inner barrel and thus effectively cleaning the core barrel just prior to cutting the core. When the barrel 22 has been cleaned in this manner, the core barrel is lowered to the well bottom and the ball valve 35 is dropped down through the drill string. This ball valve is caught by the ball catcher 33 and is directed thereby onto the valve seat 32. When seated, the ball valve prevents further discharge of circulation fluid down through the opening 31. The drill string is then rotated and lowered to cut the core in the conventional manner, and as the core is cut it enters the inner barrel 22. Circulation fluid in the inner barrel escapes ahead of the entering core through the outlet passages 25 and is carried down through the passage or space 26 and finds egress through the ports 36 in the core bit. When the inner barrel 22 has been completely filled a lifting of the core barrel by the drill string causes the core catcher 23 to grip on the core and to remove the core from the well When the core barrel is recovered at the surface it is disassembled and the core recovered.

From the above-described construction it will be appreciated that an improved core barrel is provided which is highly advantageous in that provision is made for flushing out the core barrel at or near the bottom of the well just prior to cutting the core so that the inner barrel will be clean of cuttings or other foreign material which might hinder the cutting and recovery of a complete core. After the flushing operation has taken place the inner barrel is closed against further ingress of circulation fluid so that the core will not be washed away or disturbed thereby.

Various changes may be made in the details of construction without departing from the spirit and scope of the invention as defined by the appended claims.

I claim:

1. A core barrel comprising a core bit, an outer shell connected thereto attachable to a drill string, an outer barrel mounted on the core bit and disposed within the shell in spaced relation thereto, an inner barrel disposed within the outer barrel and in spaced relation thereto, there being passages in the core bit providing for egress from the space between the outer barrel and the shell and from the space between the inner barrel and the outer barrel, respectively, there being one or more passages through the wall of the inner barrel adjacent the top thereof, a hollow stem threadedly extending through the top of the outer barrel so as to be vertically adjustable relatively thereto and extending down into the top of the inner barrel providing ingress into the top of the inner barrel, means including an anti-friction bearing connecting the top of the inner barrel to said hollow stern so that the inner barrel may rotate relatively thereto, a valve seat in the top of the hollow stern, and a ball valve adapted to be dropped through the drill string to seat upon said seat whereby prior to the dropping of the ball circulation fluid may be forced down through the hollow stern and into the inner barrel to flush out the inner barrel and after the dropping and seating of the ball further downward flow of circulation fluid through the stern and into the inner barrel is discontinued.

2. A core barrel comprising a core bit, an outer shell connected thereto attachable to a drill string, an outer barrel mounted on the core bit and disposed within the shell in spaced relation thereto, an inner barrel disposed within the outer barrel and in spaced relation thereto, there being passages in the core bit providing for egress from the space between the outer barrel and the shell and from the space between the inner barrel and the outer barrel, respectively, there being one or more passages through the wall of the inner barrel adjacent the top thereof, a hollow stem threadedly extending through the top of the outer barrel so as to be vertically adjustable relatively thereto and extending down into the top of the inner barrel providing ingress into the top of the inner barrel, means including an anti-friction bearing connecting the top of the inner barrel to said hollow stem so that the inner barrel may rotate relatively thereto, stuffing boxes between the top of the inner barrel and said hollow stem located above and below the anti-friction bearing, a valve seat at the top of the hollow stern, and a ball valve adapted to be dropped through the drill string to seat upon said seat whereby prior to the dropping of the ball circulation fluid may be forced down through the hollow stem and into the inner barrel to flush out the inner barrel and after the dropping and seating of the ball further downward flow of circulation fluid through the stem and into the inner barrel is discontinued.

References Cited in the file of this patent UNITED STATES PATENTS 

